Spindle structure for gear shaping machine or the like

A fluid operating and control mechanism for axial reciprocation of a spindle in a machine tool having a cylinder and wherein the spindle comprises a piston slidable in the cylinder and having first and second faces of respectively smaller and larger area, said spindle being provided with an axial bore, a valve reciprocable in said spindle bore and cooperating with the spindle to define first and second fluid passages in the spindle bore, conduit means including a pressure line for connection with a source of fluid under pressure and a drain line for returning fluid to the source at low pressure, the pressure line being arranged continuously to direct fluid against said first face, said first passage being disposed between said first and second faces and said second passage being disposed between said second face and said drain line, said valve being reciprocable in said first and second passages and arranged when moved in one axial direction to open said first passage and close said second passage and thereby cause movement of the spindle in said one axial direction in its working stroke and when moved in the opposite axial direction to close said first passage and open said second passage and thereby cause spindle movement in the said opposite axial direction in its return stroke, and mechanical drive means for reciprocating said valve.